A preposition is a word that indicates a relationship between a noun and some other part of the sentence. A preposition usually comes before the noun it relates to. In some languages, such as Japanese, such words come after the noun and are called postpositions.

Example:
The train goes along the line under the bridge, through many towns and arrives at the final station, on time, with many passengers on board.

In many languages, one can not use a preposition to end a sentence with. On the surface, English appears to be an exception, although many schoolteachers discourage this practice in their students. In actuality, the rule is more properly stated as: "It is in poor form to end a sentence with a preposition, unless the preposition is part of a compound verb such as 'put up with', 'see off', or 'run over'." This rule can be labeled as "stylistic" rather than "prescriptive", as the first sentence of this paragraph illustrates.